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Dermatoglyphic prints Neglected records in racial anthropology.

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Department of Anatomy, Tulane University
This is published with the hope that it may stimulate more
extensive collection of records f o r racial studies of the epidermal-ridge configurations, o r dermatoglyphs. While a sufficient amount of work has been done to demonstrate that
racial dermatoglyphic traits do exist, larger collections and
a representation of many races a r e needed. Since the prints
can be made so readily, there is reason to believe that the
need will be met when those who a r e in contact with the
material recognize the potential usefulness of these records
as well as the small outlay i n equipment and effort necessary
to obtain them.
The collection of prints is urged not only because of laggard
progress i n dermatoglyphic investigation, but also on account
of' the fact that they afford a means of extending the correlation of somatic traits within a racial sample. When circumstances admit the assembling of comprehensive records,
prints may well be secured, supplementing other records
which a r e prepared f o r later analysis in the laboratory.
Ideally, the foregoing recommendations should be accompanied by a review of what already has been accomplished,
with an indication of specific deficiences which call most
urgently for attention. It should be important to note, for
example, that our own North American Indians are not
represented in the list of published racial studies. While
a review is hardly feasible within the limits of the present
note, i t is, in fact, really unnecessary, for so little has been
done that the systematic collection of prints .within any racial
group will yield data of value. Wilder’s comment that study
in this field “. . . . has been no more than begun” is perhaps
more cogent at the present time than when it was written
in 1916, since the accomplishment since then has opened up
still more territory which awaits study. Bibliography
relating to racial studies may be consulted in several papers
appearing in previous volumes of this journal (Keith ;
Wilder; Cummins; Cummins and Midlo). An analysis of
the Eskimos is carried in the present number.
Prints of the palmar and plantar surfaces, for study of the
dermatoglyphs, possess a distinct technical advantage over
many of the records employed in physical anthropology. The
making of prints requires only the most simple and inexpensive equipment, and is, moreover, neither a very time-consuming procedure nor one necessitating detailed acquaintance
with the features recorded. Yet if the prints are to be
entirely satisfactory, it is essential to observe certain
practices in their preparation. This note provides a brief
technical guide for those who are unfamiliar with the dermatoglyphs, and it embodies such directions as the writer has
found needful in instruction in printing.
Passing t o the prints themselves, attention may be turned
first to the character of an adequate racial sample. The
number of individuals represented should naturally be as
large a s possible, since the ultimate analysis is statistical in
nature. The frequencies of various dermatoglyphic elements
a r e the chief basis of racial comparison, hence the determinations have stability in direct ratio ta the number of
individuals providing them. Ordinarily, prints of one
hundred o r more subjects should be secured, though this
statement must not be taken to discourage the collection of
prints when only a smaller series is obtainable. I n some
instances the racial characters a r e so distinctive that they
a r e reliably indicated in a limited series, and even when this
is not the case, the smaller collections represent an advance
in the assembling of d a t a - o f importance particularly in the
instance of the less commonly accessible peoples.
I t is a matter of practical interest that individuals of any
age a r e suitable subjects, the dermatoglyphs undergoing no
morphological change with growth and advancing age.
Infants, however, a r e not favorable from the standpoint of
printing technique, their hands being difficult to manage and
the ridges so delicate that prints made by the usual method
are often mere smudges. (When prints of infants a r e
desired, as in inheritance studies, the photopaper method
devised by J. H. Mathews is recommended; for a n account
of the process see Am. Jour. Phys. Anthrop., vol. 12, pp.
422 4 2 4 . )
The usual precautions to control the racial composition
of the sample should be applied, of course. I f members of
families a r e represented in the collection, the relationship
should be recorded. I n a collection assembled a s a racial
sample it is desirable to exclude close relatives, for they may
bring into the series familial peculiarities which by their
frequency mask the true racial traits.
Sexual variation in dermatoglyphics appears at present
to be an almost negligible factor in the composition of a racial
collection. Thus i t is possible to determine the racial trend
in a series composed wholly of one sex or of the sexes in any
proportion. Still, certain minor sexual differences have been
reported, and it is well to secure when possible a fairly equal
representation of the sexes.
With respect to the parts which should be printed, it may
be stated that the goal toward which to work is an actually
complete record of the dermatoglyphs in each individual :
fingers, palms, toes, and soles. There are practical difficulties in the way of securing toe prints, as may be evidenced
by the fact that the literature contains but one racial analysis
of these features (Hasebe, '18, toe prints in one hundred
Japanese). While this state of affairs should in itself be
an incentive to investigate the toe patterns, failure to secure
the impressions is no iiidication that other prints need be
foregone. A series consisting of finger prints, palm prints,
and sole prints is feasible, and effort should be made to secure
this complement of records f o r each individual. There may
be occasions, however, in which f o r one reason or another
it is impossible to print the subjects to this extent, in which
case the writer urges that the palms and fingers be obtained.
If there is choice in the matter, these prints are to be preferred, both f o r the character of the dermatoglyphs and for
ease of printing.
I n suggesting the following particulars with regard to
printing there is no intention to indicate that only such equipment and method a r e appropriate, f o r any worker will in
course of time have his own preferences. The suggestions,
however, a r e based upon actual use of various devices, and
the recommendations a r e made in accordance with their working simplicity and quality of results.
Sheets of letter size (84 x 11 inches) a r c well adapted to
the present use. Letter bond of good quality serves thc
purpose, but the prints a r e improved if made 011 smoother
paper (bond with a n enameled surface). It i s unwise to
risk the permanence of the prints by using a grade of paper
which may become tendcr with aging, but if no better is to
be had, one map conserve the prints by mounting the sheets
on a substantial backing.
The ink marketed f o r the mimeograph serves excellently
in printing, and requires 110 preparation for use. Unless it
is obtained in a collapsible tube, a small wide-mouth bottle
having a cork fitted with a brush or swab should be provided
as a container from which the ink may be daubed upon the
printing slab.
A small rubber roller is needed for spreading ink. While
the softer composition roller used by printers is especially
adapted to the purpose, the type employed in photographic
work is quite suitable.
Printing slabs
Two printing slabs provide rigid, smooth surfaces, upon
one of which ink is to be rolled, while the other serves to
support the paper while the print is being made. Glass slabs,
which are often used, are clearly unfitting if the equipment
is to be safely portable. Slabs with a working surface as
good as glass may be made by backing sheets of polished
copper, tin, or brass with wood, care being taken that the
metal is perfectly plane. The slabs must be large enough
to accommodate the foot; a length of about 12 inches is suggested, and the width should not be less than about 6 inches.
‘Pressure pad’
The palm, with its irregular reliefs, will require special
manipulation jf all its surface is registered in the print.
While other devices have been suggested, the sponge-rubber
cushion employed by Strong (Science, vol. 69, p. 250, 1929)
is recommended. Strong describes the pad as follows:
The material employed for the pressure pad is a variety of sponge
rubber bearing the trade name of ‘Spongtex,’ which is sold by
office-supply dealers in the form of chair cushions. It is about
17 mm in thickness, with plane surfaces, one of which is felt. For
the purpose under discussion it should be cut into rectangular slabs
of convenient size (e.g., 15 x 15 cm), and the felt-covered sides of
two slabs glued together with a liberal supply of Le Page’s glue,
applied to both slabs. Too much weight placed on the slabs while the
glue is drying will result in subsequent warping of the pressure pad.
To be in fit condition f o r printing, the hands and feet must
be clean and dry. (The subject may be assured that the ink
washes away readily with soap and water.) The ink slab
and roller are to be kept free from dust and grit.
The principle of dermatoglyphic printing is the same as
printing from type, involving simply the application of ink
to discrete elevations and their impression against paper.
The skin ridges are appreciably raised, adjoining ridges being
separated by distinct grooves, and it is their summits which
carry the ink in printing. A daub of ink is placed upon the
ink slab, and with the roller it is spread into a thin, uniform
film. The quantity of ink is of prime importance, the chief
need being to guard against a n excess. The optimum quantity may be determined with a few trials, and experience will
dictate the amount requisite to secure prints which show the
skin ridges clearly defined.
Transfer of ink from the film rolled on the slab to the summits of the skin ridges is effected by pressing the finger,
palm, or sole to the film; hence, if there is too much ink, it
will be squeezed into the sulci between the ridges, blurring
the resulting print. The degree of pressure applied in inking
and printing also demands notice. Excessive pressure tends
to flatten the ridges and to squeeze ink between them.
Inspection of the ink slab after an impression has been
made from it will show that the film bears a negative print
of the dermatoglyphs, since the film has been depleted at all
points of contact with the skin ridges. Should another impression be made from the film without effacing this negative
print by rolling, the second impression will surcharge it and
the print will consequently exhibit innumerable minute
lapses in the courses of the ridges. It is thus necessary to
roll the ink slab between successive impressions except in
printing the fingers, which may be impressed one after the
other on an unused portion of the film.
I n applying the finger, palm, or sole to the paper care must
be taken t o avoid dragging it while in contact, for a smudged
print is the inevitable result.
I n general, it is preferable that all the steps in printing
should be controlled by the operator alone, the subject being
directed to relax the part being printed.
A print of good quality shows the epidermal ridges cleanly
defined, and its expanse is sufficient to include all the features
of the particular area. I n making prints it is well to inspect
each one and to prepare duplicates when their need is indicated.
Methods of interpreting the dermatoglyphic features are
presented in the following selected references : palmar features, in Cummins et al., ’29, Am. Jour. Phys. Anthrop., vol.
12, pp. 4 1 5 4 7 3 ; finger prints, in Galton’s “Finger prints,”
’92, Macmillan ; plantar features, in Wilder and Wentworth,
“Personal identification,” ’18, Badger.
While it is obvious that the collector will record the customary d a t a regarding his subjects, providing each individual with an identifying number entered in the written
record, it may not be amiss to emphasize the numbering of
the prints. Every sheet of prints should carry the number of
the individual.
Of all the prints, those of the fingers a r e made with greatest
ease. They ar e prepared i n the form technically known as
‘rolled’ prints, as distinguished from ‘plain’ or ‘dab’ impressions. A plain print represents only that p a r t of the ball of
the digit which effects contact in pressing it directly against
a rigid, plane surface. Rolled prints, as the name suggests,
a r e made by rolling the terminal segment of the digit, both in
inking a n d printing, so as to include the marginal portions
which a r e lacking in plain prints.
The operator grasps the digit, the subject’s hand being
relaxed and passive, gently applies the margin of the terminal segment to the ink film, and then rocks the digit so
that the ball and opposite margin a r e successively inked.
The same rocking o r rolling motion is followed in printing,
yielding a print which includes the entire apical configuration reduced to a flat surface. It should be noted that a single
rolling accomplishes the purpose, and that its repetition
either in inking o r printing is to be avoided. The whole terminal segment should be inked and printed on its palmar and
marginal surfaces, otherwise important features of the apical
configuration may be omitted. Rolled prints usually have a
transverse dimension about double that of plain impressions
of the same digit.
The digits are printed in their natural order, being placed
most conveniently at the bottom of the sheet bearing the print
of the corresponding hand. Since the print of the whole hand
includes plain impressions of all the digits except the thumb,
the correctness of the sequence of the separate rolled prints
may be verified, and there is no need to attach identifying
marks to the separate rolled prints.
If the palm is simply pressed against the ink film and then
transferred to paper, the resulting print is commonly so incomplete as to be almost useless. Certain important dermatoglyphic features usually escape inking in this procedure :
the configuration in the central ‘hollow’ of the palm; the configurations along the distal margin, in relation to the bases
of the digits; the cohfigurations on the upturned ulnar margin; the configurations in the extreme proximal territory of
ridged skin, at the wrist. An adequate palm print may be
compared to a rolled print of the finger tip, since special precaution is taken to insure printing of the entire palm in one
continuous expanse.
Strong’s method involves the use of a resilient pressure
pad or cushion in inking and printing. Ink is applied to a
sheet of thin waxed paper, and with this resting on the pad,
the palm is pressed upon it. The cushion being yielding, the
irregular reliefs .of the palm are thus brought into contact,
and a repetition of the process, but substituting print paper,
is followed in printing. Prints thus prepared are generally
excellent in defhition, as well as complete. The results have
been found hardly less satisfactory when the cushion is employed only in printing, ink being rolled directly on the hand.
This substitute procedure saves considerable time, and its
only drawback is that an even distribution of ink is not
always attained. The Strong cushion is but one of the numerous methods which have been suggested for the same end.
Lacking the pressure pad, one may, for example, turn the
subject’s inked palm upward, lay the paper upon it, and
impress the operator’s own palm (with its axis oblique to
that of the subject’s) against the paper in such a way as to
obtain an equalized pressure throughout. Another method
involves winding the paper on a cylinder, which is then
grasped by the inked hand of the subject. A t least one print
of each hand should be complete in all respects, and this or
another print should include the fingers, naturally extended.
Attention to completeness of inking and care in impressing
the inked surface are essential.
Sole prints also may be described a s rolled and plain. A
plain sole print represents the tread area alone, and certain
features ordinarily escape registration in such prints. Four
important configuration areas occur on the ball of the foot
(hallucal and three interdigital areas), and these areas a r e
usually well displayed in plain (tread-area) prints. B y a
little added care in inking and printing, the impressions may
be rendered much more useful. The inked roller should be
passed over the region at the distal border of the sole, along
the very bases of the toes, as well as along the margins of
the foot in which ridged skin is extended upward from the
sole. By exercising ingenuity in pressing the paper against
the foot, the entire inked region may be registered in a single
print. If this procedure fails to yield a satisfactory result,
separate regional impressions should be made, especially of
the zone bordering the bases of the toes and of the fibular
margin (the latter to insure a record of the configurations in
the hypothenar area).
Toe prints, except in the instance of the great toe, are generally unsatisfactory, owing to obvious difficulties in these digits. Apparently the only solution to this refractory problem is to apply ink by cautious swabbing (with
the operator’s fingers), and to print by using small slips of
paper which may be pressed against and around the balls
of the toes, a separate slip for each print. An impression
secured in this manner should be the equivalent of a rolled
finger print. Only an occasional print will be completely successful; it is advisable, therefore, to make several impressions of each toe and to preserve all of them, since even the
best one may prove to lack some detail that may be supplied
from the duplicates. Each print requires a notation of the
digit from which it comes.
This note presents a brief technical guide for the preparation of prints of the fingers, palm, toes, and sole as records
of the dermatoglyphic features. It is introduced by a plea
that prints be obtained more generally in racial studies. Attention is directed to the fact that dermatoglyphic records
have been commonly neglected in assembling material for
racial analyses, notwithstanding the simplicity of print maki n g and the obvious utility of these records in extending the
variety of somatic traits registered f o r a racial sample.
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neglected, print, record, dermatoglyphic, Anthropology, racial
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